Allow multiple exports of the same module

CHANGELOG.md

@@ -438,14 +438,15 @@
 - [Fix performance of method calls on polyglot arrays][3781]
 - [Improved support for static and non-static builtins][3791]
 - [Missing foreign language generates proper Enso error][3798]
+- [Connecting IGV 4 Enso with Engine sources][3810]
 - [Made Vector performance to be on par with Array][3811]
 - [Introduced IO Permission Contexts][3828]
 - [Accept Array-like object seamlessly in builtins][3817]
 - [Initialize Builtins at Native Image build time][3821]
-- [Add the `Self` keyword referring to current type][3844]
 - [Split Atom suggestion entry to Type and Constructor][3835]
-- [Connecting IGV 4 Enso with Engine sources][3810]
+- [Add the `Self` keyword referring to current type][3844]
 - [Support VCS for projects in Language Server][3851]
+- [Support multiple exports of the same module][3897]
 
 [3227]: https://github.com/enso-org/enso/pull/3227
 [3248]: https://github.com/enso-org/enso/pull/3248
@@ -502,14 +503,15 @@
 [3781]: https://github.com/enso-org/enso/pull/3781
 [3791]: https://github.com/enso-org/enso/pull/3791
 [3798]: https://github.com/enso-org/enso/pull/3798
+[3810]: https://github.com/enso-org/enso/pull/3810
 [3811]: https://github.com/enso-org/enso/pull/3811
-[3828]: https://github.com/enso-org/enso/pull/3828
 [3817]: https://github.com/enso-org/enso/pull/3817
 [3821]: https://github.com/enso-org/enso/pull/3821
-[3844]: https://github.com/enso-org/enso/pull/3844
+[3828]: https://github.com/enso-org/enso/pull/3828
 [3835]: https://github.com/enso-org/enso/pull/3835
-[3810]: https://github.com/enso-org/enso/pull/3810
+[3844]: https://github.com/enso-org/enso/pull/3844
 [3851]: https://github.com/enso-org/enso/pull/3851
+[3897]: https://github.com/enso-org/enso/pull/3897
 
 # Enso 2.0.0-alpha.18 (2021-10-12)
 

build.sbt

@@ -2100,8 +2100,8 @@ buildStdLib := Def.inputTaskDyn {
   val cmd: String = allStdBits.parsed
   val root: File  = engineDistributionRoot.value
   // Ensure that a complete distribution was built at least once.
-  // Becasuse of `if` in the sbt task definition and usage of `streams.value` one has to
-  // delegate to another task defintion (sbt restriction).
+  // Because of `if` in the sbt task definition and usage of `streams.value` one has to
+  // delegate to another task definition (sbt restriction).
   if ((root / "manifest.yaml").exists) {
     pkgStdLibInternal.toTask(cmd)
   } else buildEngineDistribution

engine/runtime/src/main/scala/org/enso/compiler/Compiler.scala

@@ -105,7 +105,11 @@ class Compiler(
     */
   def runImportsResolution(module: Module): List[Module] = {
     initialize()
-    importResolver.mapImports(module)
+    try {
+      importResolver.mapImports(module)
+    } catch {
+      case e: ImportResolver.HiddenNamesConflict => reportExportConflicts(e)
+    }
   }
 
   /** Processes the provided language sources, registering any bindings in the
@@ -368,7 +372,12 @@ class Compiler(
   }
 
   private def runImportsAndExportsResolution(module: Module): List[Module] = {
-    val importedModules = importResolver.mapImports(module)
+    val importedModules =
+      try {
+        importResolver.mapImports(module)
+      } catch {
+        case e: ImportResolver.HiddenNamesConflict => reportExportConflicts(e)
+      }
 
     val requiredModules =
       try { new ExportsResolution().run(importedModules) }
@@ -818,6 +827,16 @@ class Compiler(
     }
   }
 
+  private def reportExportConflicts(exception: Throwable): Nothing = {
+    if (context.isStrictErrors) {
+      context.getOut.println("Compiler encountered errors:")
+      context.getOut.println(exception.getMessage)
+      throw new CompilationAbortedException
+    } else {
+      throw exception
+    }
+  }
+
   /** Report the errors encountered when initializing the package repository.
     *
     * @param err the package repository error

engine/runtime/src/main/scala/org/enso/compiler/data/BindingsMap.scala

@@ -255,46 +255,48 @@ case class BindingsMap(
     *         as and any further symbol restrictions.
     */
   def getDirectlyExportedModules: List[ExportedModule] =
-    resolvedImports.collect { case ResolvedImport(_, Some(exp), mod) =>
-      val hidingEnsoProject =
-        SymbolRestriction.Hiding(Set(Generated.ensoProjectMethodName))
-      val restriction = if (exp.isAll) {
-        val definedRestriction = if (exp.onlyNames.isDefined) {
+    resolvedImports.collect { case ResolvedImport(_, exports, mod) =>
+      exports.map { exp =>
+        val hidingEnsoProject =
+          SymbolRestriction.Hiding(Set(Generated.ensoProjectMethodName))
+        val restriction = if (exp.isAll) {
+          val definedRestriction = if (exp.onlyNames.isDefined) {
+            SymbolRestriction.Only(
+              exp.onlyNames.get
+                .map(name =>
+                  SymbolRestriction
+                    .AllowedResolution(name.name.toLowerCase, None)
+                )
+                .toSet
+            )
+          } else if (exp.hiddenNames.isDefined) {
+            SymbolRestriction.Hiding(
+              exp.hiddenNames.get.map(_.name.toLowerCase).toSet
+            )
+          } else {
+            SymbolRestriction.All
+          }
+          SymbolRestriction.Intersect(
+            List(hidingEnsoProject, definedRestriction)
+          )
+        } else {
           SymbolRestriction.Only(
-            exp.onlyNames.get
-              .map(name =>
-                SymbolRestriction
-                  .AllowedResolution(name.name.toLowerCase, None)
+            Set(
+              SymbolRestriction.AllowedResolution(
+                exp.getSimpleName.name.toLowerCase,
+                Some(mod)
               )
-              .toSet
-          )
-        } else if (exp.hiddenNames.isDefined) {
-          SymbolRestriction.Hiding(
-            exp.hiddenNames.get.map(_.name.toLowerCase).toSet
+            )
           )
+        }
+        val rename = if (!exp.isAll) {
+          Some(exp.getSimpleName.name)
         } else {
-          SymbolRestriction.All
+          None
         }
-        SymbolRestriction.Intersect(
-          List(hidingEnsoProject, definedRestriction)
-        )
-      } else {
-        SymbolRestriction.Only(
-          Set(
-            SymbolRestriction.AllowedResolution(
-              exp.getSimpleName.name.toLowerCase,
-              Some(mod)
-            )
-          )
-        )
+        ExportedModule(mod, rename, restriction)
       }
-      val rename = if (!exp.isAll) {
-        Some(exp.getSimpleName.name)
-      } else {
-        None
-      }
-      ExportedModule(mod, rename, restriction)
-    }
+    }.flatten
 }
 
 object BindingsMap {
@@ -675,7 +677,7 @@ object BindingsMap {
     */
   case class ResolvedImport(
     importDef: IR.Module.Scope.Import.Module,
-    exports: Option[IR.Module.Scope.Export.Module],
+    exports: List[IR.Module.Scope.Export.Module],
     target: ImportTarget
   ) {
 

engine/runtime/src/main/scala/org/enso/compiler/phase/ImportResolver.scala

@@ -28,6 +28,7 @@ import scala.collection.mutable
   * @param compiler the compiler instance for the compiling context.
   */
 class ImportResolver(compiler: Compiler) {
+  import ImportResolver._
 
   /** Runs the import mapping logic.
     *
@@ -121,8 +122,65 @@ class ImportResolver(compiler: Compiler) {
   ): (IR.Module.Scope.Import, Option[BindingsMap.ResolvedImport]) = {
     val impName = imp.name.name
     val exp = module.exports
-      .collect { case ex: Export.Module => ex }
-      .find(_.name.name == impName)
+      .collect { case ex: Export.Module if ex.name.name == impName => ex }
+    val fromAllExports = exp.filter(_.isAll)
+    fromAllExports match {
+      case _ :: _ :: _ =>
+        // Detect potential conflicts when importing all and hiding names for the exports of the same module
+        val unqualifiedImports = fromAllExports.collect {
+          case e if e.onlyNames.isEmpty => e
+        }
+        val qualifiedImports = fromAllExports.collect {
+          case IR.Module.Scope.Export.Module(
+                _,
+                _,
+                _,
+                Some(onlyNames),
+                _,
+                _,
+                _,
+                _,
+                _
+              ) =>
+            onlyNames.map(_.name)
+        }
+        val importsWithHiddenNames = fromAllExports.collect {
+          case e @ IR.Module.Scope.Export.Module(
+                _,
+                _,
+                _,
+                _,
+                Some(hiddenNames),
+                _,
+                _,
+                _,
+                _
+              ) =>
+            (e, hiddenNames)
+        }
+        importsWithHiddenNames.foreach { case (e, hidden) =>
+          val unqualifiedConflicts = unqualifiedImports.filter(_ != e)
+          if (unqualifiedConflicts.nonEmpty) {
+            throw HiddenNamesShadowUnqualifiedExport(
+              e.name.name,
+              hidden.map(_.name)
+            )
+          }
+
+          val qualifiedConflicts =
+            qualifiedImports
+              .filter(_ != e)
+              .flatten
+              .intersect(hidden.map(_.name))
+          if (qualifiedConflicts.nonEmpty) {
+            throw HiddenNamesShadowQualifiedExport(
+              e.name.name,
+              qualifiedConflicts
+            )
+          }
+        }
+      case _ =>
+    }
     val libraryName = imp.name.parts match {
       case namespace :: name :: _ =>
         LibraryName(namespace.name, name.name)
@@ -175,3 +233,37 @@ class ImportResolver(compiler: Compiler) {
     }
   }
 }
+
+object ImportResolver {
+  trait HiddenNamesConflict {
+    def getMessage(): String
+  }
+
+  private case class HiddenNamesShadowUnqualifiedExport(
+    name: String,
+    hiddenNames: List[String]
+  ) extends Exception(
+        s"""Hidden '${hiddenNames.mkString(",")}' name${if (
+          hiddenNames.size == 1
+        ) ""
+        else
+          "s"} of the export module ${name} conflict${if (hiddenNames.size == 1)
+          "s"
+        else
+          ""} with the unqualified export"""
+      )
+      with HiddenNamesConflict
+
+  private case class HiddenNamesShadowQualifiedExport(
+    name: String,
+    conflict: List[String]
+  ) extends Exception(
+        s"""Hidden '${conflict.mkString(",")}' name${if (conflict.size == 1) ""
+        else
+          "s"} of the exported module ${name} conflict${if (conflict.size == 1)
+          "s"
+        else
+          ""} with the qualified export"""
+      )
+      with HiddenNamesConflict
+}

engine/runtime/src/test/resources/Test_Multiple_Conflicting_Exports_1/package.yaml

@@ -0,0 +1,6 @@
+name: Test_Multiple_Conflicting_Exports_1
+license: APLv2
+enso-version: default
+version: "0.0.1"
+author: "Enso Team <contact@enso.org>"
+maintainer: "Enso Team <contact@enso.org>"

engine/runtime/src/test/resources/Test_Multiple_Conflicting_Exports_1/src/F1.enso

@@ -0,0 +1,2 @@
+foo = 42
+bar = "z"

engine/runtime/src/test/resources/Test_Multiple_Conflicting_Exports_1/src/F2.enso

@@ -0,0 +1,5 @@
+import project.F1
+from project.F1 import foo
+export project.F1
+from project.F1 export foo
+from project.F1 export all hiding foo

engine/runtime/src/test/resources/Test_Multiple_Conflicting_Exports_1/src/Main.enso

@@ -0,0 +1,7 @@
+from Standard.Base import IO
+from project.F2 import all
+
+main =
+    IO.println F1.bar
+    IO.println foo
+

engine/runtime/src/test/resources/Test_Multiple_Conflicting_Exports_2/package.yaml

@@ -0,0 +1,6 @@
+name: Test_Multiple_Conflicting_Exports_2
+license: APLv2
+enso-version: default
+version: "0.0.1"
+author: "Enso Team <contact@enso.org>"
+maintainer: "Enso Team <contact@enso.org>"

engine/runtime/src/test/resources/Test_Multiple_Conflicting_Exports_2/src/F1.enso

@@ -0,0 +1,2 @@
+foo = 42
+bar = "z"

engine/runtime/src/test/resources/Test_Multiple_Conflicting_Exports_2/src/F2.enso

@@ -0,0 +1,6 @@
+import project.F1
+from project.F1 import foo
+export project.F1
+
+from project.F1 export all
+from project.F1 export all hiding bar

engine/runtime/src/test/resources/Test_Multiple_Conflicting_Exports_2/src/Main.enso

@@ -0,0 +1,7 @@
+from Standard.Base import IO
+from project.F2 import all
+
+main =
+    IO.println F1.bar
+    IO.println foo
+

engine/runtime/src/test/resources/Test_Multiple_Exports/package.yaml

@@ -0,0 +1,6 @@
+name: Test_Multiple_Exports
+license: APLv2
+enso-version: default
+version: "0.0.1"
+author: "Enso Team <contact@enso.org>"
+maintainer: "Enso Team <contact@enso.org>"

engine/runtime/src/test/resources/Test_Multiple_Exports/src/F1.enso

@@ -0,0 +1,2 @@
+foo = 42
+bar = "z"

engine/runtime/src/test/resources/Test_Multiple_Exports/src/F2.enso

@@ -0,0 +1,4 @@
+import project.F1
+from project.F1 import foo
+export project.F1
+from project.F1 export foo

engine/runtime/src/test/resources/Test_Multiple_Exports/src/Main.enso

@@ -0,0 +1,7 @@
+from Standard.Base import IO
+from project.F2 import all
+
+main =
+    IO.println F1.bar
+    IO.println foo
+    0